U.S. patent number 5,116,937 [Application Number 07/709,920] was granted by the patent office on 1992-05-26 for water-swellable thermoplastic copolyetherester elastomer.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Robin N. Greene.
United States Patent |
5,116,937 |
Greene |
May 26, 1992 |
Water-swellable thermoplastic copolyetherester elastomer
Abstract
A segmented copolyetherester elastomer has soft segments formed
from 60-95% poly(ethylene oxide) glycol and 40-45% of a second
poly(alkylene oxide)glycol, preferably poly(tetramethylene oxide)
glycol, and hard segments formed from terephthalic acid and
ethylene glycol or 1,4-butane diol, the hard segments amounting to
8-20% of the elastomer weight. The elastomer can be molded into
soft, elastic objects and can absorb water amounting to at least
100% of its dry weight.
Inventors: |
Greene; Robin N. (Rockland,
DE) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
24851842 |
Appl.
No.: |
07/709,920 |
Filed: |
May 31, 1991 |
Current U.S.
Class: |
528/272; 528/298;
528/300; 528/301; 528/302; 528/308; 528/308.6 |
Current CPC
Class: |
C08G
63/672 (20130101) |
Current International
Class: |
C08G
63/00 (20060101); C08G 63/672 (20060101); C08G
063/20 () |
Field of
Search: |
;528/272,298,300,301,302,308,308.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kight, III; John
Assistant Examiner: Acquah; Sam A.
Claims
I claim:
1. A thermoplastic, segmented copolyetherester elastomer which
consists essentially of a multiplicity of recurring intralinear
long-chain and short-chain ester units connected head-to-tail
through ester linkages, wherein
the long-chain ester units amount to 80 to 92 weight percent of the
elastomer and are represented by the structure ##STR3## and the
short-chain ester units amount to 20 to 8 weight percent and are
represented by the structure ##STR4## and wherein R represents a
divalent radical which remains after removal of two carboxyl groups
from a dicarboxylic acid selected from the group consisting of
terephthalic acid, 4,4'-bibenzoic acid, 2,6-naphthalenedicarboxylic
acid and mixtures thereof,
G is a divalent radical which remains after removal of two hydroxyl
groups from a long chain poly(alkylene oxide) glycol having a
number average molecular weight in the range of 1,000 to 3,500 and
consisting essentially of 60 to 95 weight percent of poly(ethylene
oxide) glycol copolymerized or mixed with 40 to 5 percent of a
second poly(alkylene oxide) glycol, and
D is a divalent radical which remains after removal of terminal
hydroxyl groups from a short chain diol selected from the the group
consisting of ethylene glycol, 1,3-propane glycol, 1,4-butane diol
and mixtures thereof.
2. An elastomer of claim 1 wherein the poly(ethylene oxide) glycol
amounts to at least 70 weight percent of the poly(alkylene oxide)
glycol and the second poly(alkylene oxide) glycol is
poly(tetramethylen oxide) glycol.
3. An elastomer of claim 1 wherein the long chain ester units
amount to 85 to 90 weight percent of the elastomer, the short chain
ester units amount to 15 to 10 weight percent, and the number
average molecular weight of the poly(alkylene oxide) glycol is in
the range of 1,400 to 2,000.
4. An elastomer of claim 1, 2 or 3 wherein the short chain ester
unit is derived from ethylene glycol and terephthalic acid and the
molar ratio of hard segment to soft segment in the elastomer is in
the range of 1 to 3.
5. An elastomer of claim 4, wherein the molar ratio is in the range
of 1.3 to 2.2.
6. An elastomer of claim 1, 2 or 3 wherein the short chain ester
unit is derived from 1,4-butane diol and terephthalic acid and the
molar ratio of hard segment to soft segment in the elastomer is in
the range of 0.3 to 1.3.
7. An elastomer of claim 6, wherein the molar ratio is in the range
of 0.8 to 1.2.
8. An elastomer of claim 1, 2 or 3 wherein the short chain ester
unit is derived from 1,4-butane diol and 2,6-naphthalene
dicarboxylic acid and the molar ratio of hard segments to soft
segments is the range of 0.3 to 1.3.
9. An elastomer of claim 8, wherein the molar ratio is in the range
of 0.8 to 1.2.
10. An elastomer of claim 1 or 2 or 3 wherein the short chain ester
unit is derived from 1,3-propane diol and 4,4'-bibenzoic acid and
the ratio of hard segments to soft segments is the range of 0.3 to
1.3.
11. An elastomer of claim 10, wherein the molar ratio is in the
range of 0.3 to 0.7.
12. An elastomer of claim 1, 2 or 3 in the form of a shaped
article.
13. An elastomer of claim 12 which imbibes water amounting to at
least 100% of its dry weight as a result of immersion in water for
24 hours.
14. A shaped article of claim 12 containing water amounting to at
least 100% of its dry weight in the shape of an artificial
worm-like fishing lure.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a thermoplastic, hydrophilic, segmented,
copolyesterether elastomer. More particularly, the invention
concerns such an elastomer having certain soft segments that are
long chain ester units formed from poly(alkylene oxide) glycols and
certain hard segments that are short chain ester units formed from
diols and dicarboxylic acids, esters or ester-forming derivatives.
The elastomers, when swollen with imbibed water, are particularly
suited for use in artificial fishing lures, wet wound-dressings,
and the like. 2. Description of the Prior Art
Shivers, U.S. Pat. No. 3,023,192, discloses hydrophilic,
thermoplastic, segmented copolyetherester elastomers having soft
and hard segments. The soft segments constitute about 35 to about
75% of the elastomer weight and are derived from a poly(alkylene
oxide) glycol, such as poly(ethylene oxide) glycol, poly(propylene
oxide) glycol, poly(tetramethylene oxide) glycol and mixtures
thereof, preferably a poly(tetramethylene oxide) glycol. The hard
segments constitute 65 to 25% of the elastomer and are derived from
an aromatic dicarboxylic acid, such as terephthalic, isophthalic,
bibenzoic, naphthalene dicarboxylic, and mixtures thereof,
preferably terephthalic acid. Shivers discloses at column 10, lines
45-68, that many of his elastomers are hydrophilic. However, the
polyetherester elastomers disclosed by Shivers, are inadequate for
certain specialty applications, such as those that require the
elastomer to imbibe large quantities of water and still have
adequate elasticity and strength. An object of this invention is to
provide a copolyetherester elastomer that overcomes or at least
significantly reduces the aforementioned inadequacies.
SUMMARY OF THE INVENTION
The present invention provides a thermoplastic, segmented
copolyetherester elastomer which consists essentially of a
multiplicity of recurring intralinear long-chain and short-chain
ester units connected head-to-tail through ester linkages,
wherein
the long-chain ester units amount to 80 to 92 weight percent of the
elastomer and are represented by the structure ##STR1## and
the short-chain ester units amount to 20 to 8 weight percent and
are represented by the structure ##STR2## and wherein
R is a divalent radical which remains after removal of two carboxyl
groups from a dicarboxylic acid selected from the group consisting
of terephthalic acid, 4,4'-bibenzoic acid,
2,6-naphthalenedicarboxylic acid and mixtures thereof,
G is a divalent radical which remains after removal of two hydroxyl
groups from a long chain poly(alkylene oxide) glycol having a
number average molecular weight in the range of 1,000 to 3,500 and
consisting essentially of 60 to 95 weight percent of poly(ethylene
oxide) glycol copolymerized or mixed with 40 to 5 percent of a
second poly(alkylene oxide) glycol, and
D is a divalent radical which remains after removal of terminal
hydroxyl groups from a short chain diol selected from the group
consisting of ethylene glycol, 1,3-propane glycol, 1,4-butane diol
and mixtures thereof. A preferred second poly(alkylene oxide)
glycol is poly(tetramethylene oxide) glycol.
The present invention also provides fibers, films, and molded
articles of the above-described elastomer, including a molded
article in the form of a water-swellable, worm-shaped, artificial
fishing lure, and processes for its manufacture and treatment. Such
articles of the invention absorb water in amounts equal to at least
the dry weight of the elastomer and exhibit satisfactory strength
and elastic properties.
BRIEF DESCRIPTION OF THE DRAWING
The attached drawing is a side-view of an article molded from
elastomer of the invention. The article is generally circular in
cross-section and is intended, when swollen with imbibed water, for
use as an artificial worm-like fishing lure.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The elastomer of the invention consists essentially of long chain
ester units, which constitute the "soft segments" of the elastomer,
and short chain ester units, which constitute the "hard segments"
of the elastomer.
In accordance with the present invention, the long chain ester
units, or soft segments, of the elastomer constitute 80 to 92
percent of the total elastomer weight, preferably 85 to 90%. These
segments are formed by reacting terephthalic acid, 4,4'-bibenzoic
acid, 2,6-naphthalene dicarboxylic acid or mixtures thereof with an
oligomeric poly(alkylene oxide) glycol to form a long chain
polymeric glycol ester. The poly(alkylene oxide) glycol consists
essentially of 60 to 95 weight percent poly(ethylene oxide) glycol
mixed or copolymerized with 40 to 5 weight percent of a second
poly(alkylene oxide) glycol, preferably poly(tetra- methylene
oxide) glycol. Preferably, the poly(alkylene oxide) glycol is at
least 70% poly(ethylene oxide) glycol. The long chain oligomeric
glycol has terminal (or as nearly terminal as possible) hydroxyl
groups and a molecular weight that is usually in the range of about
1,000 to 3,500, preferably 1,400 to 2,000. Within these ranges,
broad or narrow molecular weight distributions are suitable for use
in the invention. When incorporated into the elastomer, the long
chain oligomeric glycol forms long chain ester repeating units
(soft segments) of the elastomer structure shown in Formula I
above.
The desired mole percent of ethylene oxide comonomer can be
obtained by blending oligomeric glycols or by using ethylene
oxide/alkylene oxide copolymer oligomeric glycols. For example, a
blend can be made of a glycol having a high content of the
comonomer with a glycol having a lower comonomer content or no
comonmer at all. The desired molecular weight of the glycol can be
similarly obtained by blending.
The short chain ester units, or hard segments, are formed by
reacting terephthalic acid, or 4,4'-bibenzoic acid or
2,6-naphthalenedicarboxylic acid or mixtures thereof with ethylene
glycol, 1,3-propane diol, or 1,4-butane diol, to form a polyester.
When incorporated into the elastomer, the polyester forms the short
chain ester repeating units (hard segments) of the structure shown
in Formula II above. Usually, the hard segments of the elastomers
constitute 8 to 20 percent of the total elastomer weight,
preferably 10 to 15%. Hard segments of preferred elastomers of the
invention are formed from (a) ethylene glycol and terephthalic acid
or (b) 1,4-butane diol and terephthalic acid.
The mole ratio of hard segment to soft segment in elastomers of the
invention depends on the composition of the hard segment, as noted
in the following list:
______________________________________ HS/SS Range HS Usual
Preferred ______________________________________ 2G/T 1-3 1.3-2.2
4G/T 0.3-1.3 0.8-1.2 4G/N 0.3-1.3 0.8-1.2 3G/BB 0.3-1.3 0.3-0.7
______________________________________
When the HS/SS ratio of the elastomer is below the stated minimum
value of the range, the elastomer usually possesses undesirably low
tensile and tear strengths. As the HS/SS ratio is increased within
the preferred range, the strengths usually improve. When HS/SS
ratio is greater than the stated maximum value of the range,
water-soaked molded objects of the elastomer become stiff and hard
due to insufficient imbibing of water.
Note that small amounts of other diols or diacids can be included
in the hard segments, usually amounting to no more than 15 weight
percent of structural formula II above. Such small amounts have
little detrimental effect on the desirable properties of
water-swollen elastomers of the invention.
The preceding discussion refers to terephthalic acid,
4,4'-bibenzoic acid, 2,6-naphthalenedicarboxylic acid, for reaction
with oligomeric glycols or diols, to form the required soft and
hard segments of the elastomer of the invention. As used herein,
these dicarboxylic acids are intended to include equivalents, which
have two functional carboxyl groups and perform substantially like
dicarboxylic acids in reaction with glycols and diols to form
copolyetherester polymers. Such equivalents include esters and
ester-forming derivatives (e.g., acid halides and anhydrides).
The elastomers of the invention can be produced by first preparing
a prepolymer by conventional ester interchange and then increasing
the molecular weight of the prepolymer by conventional
polycondensation. For example, the prepolymer can be prepared by
heating the dimethyl ester of terephthalic acid or of
2,6-naphthalene dicarboxylic acid with a long chain glycol and an
excess of diol in the presence of a catalyst at
150.degree.-260.degree. C., while distilling off methanol formed by
the ester interchange. Depending on temperature, catalyst, glycol
excess, and equipment, the reaction can be completed within a few
minutes to a few hours. This procedure results in a prepolymer
which can be increased in molecular weight by the procedure
described below.
The desired prepolymers can also be prepared by other known
alternative esterification or ester interchange processes. For
example, the long chain glycol can be reacted with a low molecular
weight, short chain ester homopolymer or copolymer, in the presence
of catalyst, until randomization occurs. The short chain ester
homopolymer or copolymer can be prepared by ester interchange from
the dimethyl esters and low molecular weight diols, as above, or
from the free acids with diol acetates. Alternatively, the short
chain ester copolymer can be prepared by direct esterification from
suitable acids, anhydrides, or acid chlorides, for example, with
diols, or by reaction of the acids with cyclic ethers or
carbonates. The prepolymer could also be prepared by performing the
reactions in the presence of a long chain glycol.
The prepolymers described in the preceding two paragraphs can be
carried to high molecular weight by known polycondensation
processes, in which excess short chain diol is distilled off.
Further ester interchange occurs during such polycondensation or
distillation and serves to increase molecular weight and randomize
the arrangement of the copolyester units. Best results are usually
obtained when the final distillation or polycondensation is
conducted at a pressure of less than 5 mm Hg and at a temperature
of about 220.degree.-260.degree. C. for less than 6 hours (e.g.,
0.5 to 5 hours) in the presence of conventional antioxidants.
Practical polymerization techniques usually rely upon ester
interchange to complete the polymerization. To avoid excessive time
at high temperatures and possible accompanying thermal degradation,
a catalyst can be employed in the ester interchange. Preferred
catalysts are tetrabutyl titanate and/or butylstannoic acid.
Ester interchange polymerizations are generally conducted in the
melt without added solvent, but inert solvents can be added to
facilitate removal of volatile components at low temperatures. This
technique is especially valuable during prepolymer preparation by
direct esterification. Other special polymerization techniques can
be useful for preparation of specific polymers. Polycondensation of
prepolymer can also be accomplished in the solid phase by heating
divided solid prepolymer in a vacuum or in a stream of inert gas to
remove liberated low molecular weight diol.
Batch or continuous methods can be used for the processes described
above or for any stage of the elastomer preparation. Continuous
polymerization, by ester interchange with a prepolymer, is a well
established commercial process and usually is preferred. To
increase the melt strength of elastomers of the invention,
branching agents are sometimes incorporated into the elastomer,
usually in a concentration of 0.01 to 0.03 equivalents per kilogram
of polymer. The branching agent can be a polyol having 3-6 hydroxyl
groups, a polycarboxylic acid having 3 or 4 carboxyl groups or a
hydroxyacid having a total of 3-6 hydroxyl and carboxyl groups.
Representative polyol branching agents include glycerol,
pentaerytritol, sorbitol, trimethylol propane, 1,2,6-hexanetriol
and 1,1,4,4-tetrakis(hydroxymethyl)cyclohexane. Representative acid
branching agents include trimesic, hemimellitic, trimellitic,
pyromellitic, 1,1,2,2-ethanetetracarboxylic,
1,1,2-ethanetricarboxylic, 1,3,5-pentanetricarboxylic,
1,2,3,4-cyclopentanetetracarboxylic acids and the like. The acids
can be used as is, but usually are preferred in the form of lower
alkyl esters.
Conventional additives (e.g., pigments, fillers, antioxidants,
ultraviolet light stabilizers, etc.) can be incorporated in the
elastomers by known techniques. The elastomers can be formed into
shaped articles by melt spinning, injection molding or compression
molding. For special purposes, such for use as worm-like fishing
lures made from water-swollen elastomer of the invention, garlic,
salt, sugar, food additives, flavorings, scents and the like also
can be added to the elastomer. To imbibe these ingredients into the
elastomer, the shaped elastomer is soaked in an 1-10% aqueous
solution of the ingredient. Also, conventional or copolymerizable
dyes and/or light-reflecting particles can be incorporated during
or after polymerization.
For convenience, several abbreviations are used herein, as
follows:
2G/T: hard segment formed from ethylene glycol (2G) and
terephthalic acid (T)
4G/T: hard segment formed from 1,4-butane diol (4G) and
terephthalic acid
4G/N: hard segment formed from 1,4-butane diol and 2,6-naphthalene
dicarboxylic acid (N)
3G/BB: hard segment formed from 1,3-propane diol (3G) and
4,4'-bibenzoic acid (BB)
PO2G: poly(ethylene oxide) glycol, also called PEO
PO3G: poly(1,2-propylene oxide) glycol
PO4G: poly(tetramethylene oxide) glycol, also called PTMEG or
poly(tetramethyleneether) glycol
DMBB: dimethyl bibenzoate
DMI: dimethyl isophthalate
DMN: dimethyl 2,6-naphthalene dicarboxylate
DMT: dimethyl terephthalate
TPA: oligomer of terephthalic acid (TPA) and ethylene glycol, for
purposes of calculation, the formula weight is taken as 192.
AO-330: 1,3,5-trimethyl-2,4,6-tris [3,5-di-t-butyl
4-hydroxy-benzyl]benzene antioxidant sold by Ethyl Corporation
TBT: tributyl titanate transesterification catalyst
BSA: butylstannoic acid catalyst
TMTM: trimethyltrimellitate, a branching agent
SS: soft segment of elastomer
HS: hard segment of elastomer
HS/SS: mole ratio of hard to soft segment
%HS: percent hard segment (based on total weight of elastomer)
MW: number average molecular weight of the long chain glycol
(corrected for content of oligomeric cyclic alkylene oxides)
Test Procedures
Various characteristics and properties mentioned in the preceding
discussion and in the Examples below were determined by the
following test procedures.
The concentration of hard segment in elastomer of the invention is
calculated by the formula, ##EQU1## wherein
w is weight,
M is molecular weight
and subscripts
hs refers to hard segment (short chain ester),
ss refers to soft segment (long chain ester),
1 refers to the dimethyl ester of starting diacid and
2 refers to the long chain glycol.
Note that the weight of the long chain glycol, as used in the
formula, must have the weight of inert oligomeric cyclic ethers
subtracted from the total weight of the glycol. Such oligomeric
ethers usually amount to about two weight percent of
poly(tetramethylene oxide) glycols made by polymerization of
tetrahydrofuran. Smaller amounts of other hard segment monomers,
derived from small amounts of another "hard" acid (e.g., 4G/N in a
polymer in which the major hard segment combination is 4G/T) are
considered to be part of the soft segment. Smaller amounts of other
hard segment monomers derived from small amounts of another "hard"
diol (e.g., 2G/T in a polymer in which the major hard segment
combination is 4G/T) are considered to be part of the soft segment.
The ratio of 2G/T to 4G/T must be determined by analyzing the
resultant polymer (e.g., by nuclear magnetic resonance), rather
than from the starting proportions of 2G and 4G used in the
polymerization, because 2G boils off preferentially during the
vacuum cycle.
Number average molecular weight of the glycol is determined by
reacting the glycol with an excess of acetic anhydride in pyridine
and then back-titrating with sodium hydroxide to measure the amount
of acetic acid produced.
Water content of the elastomer is measured with a Du Pont Model
1090 Thermogravimetric Analyzer (TGA), by raising the temperature
of a water-swollen sample from room temperature to 200.degree. C.
at 20.degree. C./min. Such an analysis is described, for example,
by B. Wunderlich, "Thermal Analysis", Rensselaer Polytechnic
Institute (1981). The water content is defined as the weight loss
of the sample as it reaches 200.degree. C. In the examples, the
water imbibed by an elastomer is given as a percent of the dry
weight of the elastomer.
All water-swellable elastomers of this invention can contain water
equal in weight to at least the weight of the dry elastomer itself.
Also, the elastomers of the invention, when containing water equal
to its dry weight, can recover at least 80% from a stretch of
100%.
The examples which follow are illustrative of the present invention
and are not intended to limit the scope, which is defined by the
claims.
EXAMPLES
The following examples describe the production of various
hydrophilic elastomers in accordance with the invention. The hard
segments of the elastomers of Examples 1-5 are of 2G/T; those of
Examples 6-8, of 4G/T; those of Example 9, of 4G/N; and those of
Example 10, of 3G/BB. Molded samples were made of the elastomer of
each example. The amount of water imbibed by the samples as a
result of being immersed in water at room temperature for 24 hours
was measured. The adequacy of the elastomeric characteristics of
the samples was established.
The same equipment and general procedures were used for preparing
each elastomer of the examples. A stainless steel kettle of
0.3-liter capacity was equipped for distillation and fitted with a
stainless steel stirrer that had a paddle that was shaped to
conform to the internal radius of the kettle. The paddle was
positioned about 0.3 cm (1/8 inch) from the bottom of the kettle.
After ingredients were charged to the kettle, the stirrer was
started. The kettle and its contents were then placed in a Woods
metal bath and heated to 244C for 40 minutes, during which time
stirring was continued and methanol was distilled from the mix. The
pressure in the system was then reduced over the course of about an
hour to 0.3 mm of mercury. Distillation was continued at the
reduced pressure for about another hour. The resulting viscous
molten product was removed from the kettle and allowed to cool. The
inherent viscosity of the elastomers produced in the examples
(measured in a solution of 0.5 gram of elastomer in 100 ml of
m-cresol at 30.degree. C., by the method of W. R. Sorenson and T.
W. Campbell, "Preparative Methods of Polymer Chemistry",
Interscience Publishers, 2nd ed., page 44, (1968)) were usually in
the range of about 1.0 to 1.6 dL/g.
Compression molded samples of each elastomer were made for further
testing. For each sample, about 5 grams of molten elastomer product
was placed within a cavity mold that had been sprayed with
"RemGrit" TFL50, a release agent, and compression molded with a
hydraulic press at a temperature of 130.degree. C. and a pressure
of at 1400 psig (9,646 kPa) for one minute. After cooling to
50.degree. C., a small worm-like molded article was removed from
the mold. The article, which is illustrated in FIG. 1, measured 2
5/8-inches (6.67-cm) long by 1/8 inch (0.32 cm) in diameter with a
thinner "curly" tail of about 7/8-inch (2,2-cm) length and
0.024-inch (0.06-cm) diameter. The molded elastomer was then soaked
in water for a day and its water-imbibing characteristics were then
determined.
For the preparations described below, the number average molecular
weights for the starting glycols were 1,540 for PO2G and 1,800 for
PO4G, except for Example 4, in which the molecular weights were
3,400 and 2,000, respectively, and Example 8, in which they were
1,000 and 2,000 respectively. Note that the ingredients for each
elastomer preparation included 1.5 ml of 5% by weight of tributyl
titanate esterification catalyst (TBT) in n-butanol and 1.0 ml of
1% by weight of butylstannoic acid catalyst (BSA) in methanol. All
other ingredients are listed Tables I, II and III.
In the tables, MW is number average molecular weight of the
oligomeric starting glycols, corrected for their oligomeric cyclic
ether content; % HS is the weight percent of 2G/T or 4G/T hard
segment in the elastomer; HS/SS is the molar ratio of hard segment
to soft segment in the elastomer; and % H.sub.2 O is the amount of
water imbibed by the elastomer when soaked in water for 24
hours.
Further details of each preparation and resultant elastomer are
given in each example. Each elastomer of the invention was capable
of imbibing water amounting to at least 100% of its dry weight and
had satisfactory tensile, tear, tactile and elastomeric
properties.
EXAMPLES 1-5
In these examples, five samples of elastomer of the invention were
prepared by the general procedure described above. Each elastomer
had 2G/T hard segments that were formed from ethylene glycol and
terephthalic acid or a derivative thereof. Table I lists the
weights (in grams) of ingredients used to make the elastomers.
Example 2 employed the same general procedure as the other
examples, except that after the Woods metal bath had cooled to
125.degree. C., 100 ml of water were added and the polymer/water
mixture was stirred, while at a temperature of 125.degree. C., for
1 hour and 35 minutes.
In Example 3, the water-absorbing property of the elastomer was
further tested. Small pieces of elastomer were soaked in 1, 2, 3
and 5% aqueous solutions of sodium chloride for 24-hours. The
elastomer samples that were soaked in salt water absorbed between
200 and 220% of the elastomer dry weight. The weight of water
absorbed when soaked for the same period of time in pure water was
290%.
Several additional polymerizations were performed in the same way,
except that when the polymerizations were nearly complete (i.e.,
the torque on the stirrer was near at its maximum and
polymerization was within a half-hour of completion), nitrogen gas
was introduced into the kettle to return the pressure to
atmospheric. By adding two drops of different dyes (e.g.,
"Reactint") at that time, re-establishing the vacuum in the kettle
and then completing the polymerization, and then molding articles
of the kind illustrated in FIG. 1, elastomer samples of a variety
of colors (e.g., pink. blue, yellow, purple) were produced. A
further fluorescent yellow color ("Akazol") was added by dipping
the tail of the molded object into a solution of the dye in
methanol. These dyed molded elastomer samples were swollen by being
immersed in water for over 24 hours and then used by expert
fishermen as fishing worm lures in a comparison test against other
commercial plastic "worm" lures. In this test, no fish were caught
with the known commercial lures. In contrast, fishing in the same
waters at the same time with water-swollen fishing lures of the
invention resulted in two bass being caught and one large pickerel
biting at the lure and cutting the fishing line with its sharp
teeth.
Further details of the elastomers are given in Table I.
TABLE I
__________________________________________________________________________
Elastomers with 2G/T hard segments Example No. 1 2 3 4 5
__________________________________________________________________________
Ingredients, grams.sup.(1) PO2G 40.0 40.0 40.0 23.7 21.2 PO4G 5.0
5.0 5.0 10.4 9.3 2G 10.0 10.0 8.0 10.0 10.0 TPA 14.2 14.2 13.8 --
11.0 DMT -- -- -- 7.0 -- DMI 0.2 0.2 0.2 -- -- DMN 0.2 0.2 0.0 0.0
0.0 TMTM 0.08 0.08 0.08 0.0 0.0 AO-330 0.2 0.2 0.15 0.15 0.15 Other
-- -- -- -- (2) Characteristics Molecular weight 1,568 1,568 1,568
2,817 1,618 % HS 15.0 15.0 14.4 11.6 17.2 HS/SS 1.48 1.48 1.42 2.0
2.0 % water imbibed 168 201 291 237 129
__________________________________________________________________________
Notes .sup.(1) -- means none of this ingredient added. .sup.(2) For
Example 5, 2.0 grams of a mixture of 76% dimethylglutarate and 24%
dimethyladipate was added to the ingredients.
EXAMPLES 6-8
In these examples, elastomers with 4G/T hard segments were made by
the general method described above. The ingredients used for the
preparations and the characteristics of the resultant elastomers of
the invention are summarized in Table II.
TABLE II ______________________________________ Elastomers with
4G/T hard segments Example Number 6 7 8
______________________________________ Ingredients, grams PO2G 22.7
22.7 27.3 PO4G 10.0 10.6 3.1 4G 8.0 8.0 10.0 DMT 8.2 7.5 10.5 DMI
0.5 -- -- DMN -- 4.0 2.5 TMTM 0.08 0.08 0.08 AO-330 0.15 0.15 0.15
Characteristics Molecular weight 1,618 1,610 1,053 % HS 12.2 11.0
16.7 HS/SS 1.10 1.07 1.04 % water imbibed 137 126 100
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In Examples 7 and 8, films were cast from solutions of the
elastomers in acetone and water. The films were then cut into
strips. Tensile strengths (in grams/denier converted to
deciNewtons/tex) and break elongations (in %) of the samples were
measured dry and wet (after soaking in water 24 hours). The
measurements were as follows:
______________________________________ Ex. 7 Ex. 8
______________________________________ Tenacity, dN/tex, Wet 0.014
0.008 Dry 0.021 0.015 Break Elongation, Wet 132% 49% Dry 342% 77%
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Although the elastomers became weaker in the fully water-soaked
condition, the elastomers of the invention were nonetheless
admirably suited for molded fishing lures. The softer and
aqueous-filled nature of such lures of elastomer of the invention
apparently were more palatable to fish than similar conventional
plastic lures which contain organic plasticizers. The lures of
elastomers of the invention could be firmly affixed to fish hooks
with no difficulty.
EXAMPLES 9-10
Elastomers of the invention, having hard segments of 4G/N (Example
9) and 3G/BB (Example 10), were prepared by the general procedure
described in the preceding examples, but with the ingredients
listed in Table III. Table III also lists some of the
characteristics of the resultant elastomers.
TABLE III ______________________________________ Elastomers with
4G/N and 3G/BB hard segments Example Number 9 10
______________________________________ Hard segment 4G/N 3G/BB
Ingredients, grams PO2G 22.2 16.7 PO4G 9.7 7.3 4G 8.0 -- DMN 9.1 --
3G -- 8.0 DMBB -- 7.0 TMTM -- 0.06 AO-330 0.15 0.15 Characteristics
Molecular weight 1,618 1,618 % HS 12.0 8.1 HS/SS 0.9 0.5 % water
imbibed 151 124 ______________________________________
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